In numerous operations involving at least one remote unit, that are not bound to a single fixed position, there is often a need for means for reporting on a global basis the status of a remote unit, and its global location at the moment of reporting. The term "status" as here used may relate to any condition or event at the remote unit such as for example an emergency condition, lack of operability for any reason, or simply a non-problem status.
Various status and position reporting systems are known in the prior art. As an example, U.S. Pat. No. 5,223,844, Mansell et al., shows a vehicle tracking and security system wherein a fleet of vehicles maintain communication via commercial or police radio with a control center, and wherein each vehicle obtains position data from a direct link with global positioning satellites (GPS).
Such a system has the drawbacks that no prearranged provision is made for contacting a particular base that is best suited to handle an emergency, considering the type of emergency and the global position. U.S. Pat. No. 5,225,842, Brown et al., shows a vehicle tracking system for reporting very precise vehicle positions using a position correction system, with its corrections received via a communication link. This system has the further drawback that no reporting facility is provided for reporting combined status and position information. U.S. Pat. No. 5,043,736, Darnell et al., shows a cellular position locating system, wherein a remote unit maintains a record of its global position by means of a GPS receiver in the remote unit. The remote unit also maintains communication with a base unit via a cellular radio link and a modem in the remote unit.
Although the prior art shows various versions of status and position reporting systems, none of the prior art is arranged to automatically select a particular base station based on combined status and position information, so that any type of event, emergency or particular status that may occur at the remote unit can be automatically reported to a particular base equipped to respond to the event, status or emergency.